<!DOCTYPE html>
<html>
    <head>
        <style>
            body, html {
            margin: 0;
            width: 100%;
            height: 100%;
        }
        .left, .right {
            position: relative;
        }
        .left {
            width: 30%;
            height: 100%;
            background: #448EF6;
        }
        .right {
            width: 70%;
            left: 30%;
            height: 100%;
            background: #FFE981;
            bottom: 100%;
        }
            
        </style>

    </head>
    <body>
        <div class="left"> left</div>
        <div class="right"> right</div>
    </body>
</html>